Production of motor and jet fuels

ABSTRACT

Good yields of high-quality motor fuel and jet fuel are obtained by solvent extracting a gas oil to produce a paraffin-rich raffinate and an aromatic-rich extract, hydrocracking the raffinate using a catalyst having an amorphous support, separately hydrocracking the extract using a catalyst containing a crystalline zeolitic support and recovering jet and motor fuels from the respective hydrocracker effluents.

United States Patent Robertson et al.

[151 3,642,611 [451 Feb. 15,1972

154] PRODUCTION OF MOTOR AND JET FUELS [72] Inventors: Odes B.Robertson, Groves; Thomas A. Cooper, Port Arthur, both of Tex.; Henry D.Moorer, Richmond, Va.

[73] Assignee: Texaco Inc., New York, NY.

[22] Filed: Dec. 23, 1969 211 Appl. No.: 887,720

[52] US. Cl ..208/87, 208/15, 208/78,

[51] Int. Cl ..Cl0g 13/02 [58] Field ofSearch ..208/15,78, 80, 87, 111

[56] References Cited UNITED STATES PATENTS 2,627,495 2/1953 Lanning..208/80 Primary Examiner-l-lerbert Levine AttorneyThomas H. Whaley,Carl G. Ries and Robert Knox, Jr.

[57] ABSTRACT Good yields of high-quality motor fuel and jet fuel areob- 9 Claims, No Drawings PRODUCTION OF MOTOR AND JET FUELS Thisinvention is concerned with the production of gasoline and jet fuel.More particularly it relates to a method for the simultaneous productionof jet fuel and gasoline.

Up until recently gasoline or motor fuel was by far the greatest demandproduct of the petroleum industry and accordingly it was desirable toget the maximum yield of gasoline per barrel of crude oil. To this end,most refineries were designed to convert those fractions boiling betweenabout 450 F. and the lube oil range, i.e., the gas oil fractions, intogasoline and this was accomplished, for the most part, by fluidcatalytic cracking. in the cracking of petroleum fractions, it iscustomary to recycle unconverted material to the cracking unit buteventually this recycled fraction, known as cycle gas oil, becomes sorefractory and difficult to crack that a portion of it is withdrawn andsold as distillate fuel. However, with-the advent of jet engines,fractions having an initial boiling point of from 350-400 F. and an endpoint of about 525 F. have come into great demand as jet fuels. It hastherefore now become customary to charge virgin gas oils to fluidcatalytical cracking units and recover from the cracking unit as productbath gasoline and jet fuel and to recycle to the cracking unit thatfraction of the effluent boiling above the jet fuel range. However, forthe most part this process is unsatisfactory in that to meet the everincreasing jet fuel demands the gasoline end point must be compromisedwith jet fuel quality and/or product demands. This generally results ina gasoline having an end point of about350 F. which means an overallreduction in the amount of gasoline produced. Moreover, because of itslow lurninometer number, the jet fuel fraction of the cycle gas oil isnot completely satisfactory for use in jet aircraft engines.

It is an object of the present invention to provide a process for theproduction of motor fuel and jet fuel which comprises subjecting apetroleum hydrocarbon liquid having an initial boiling point of at leastabout 5,000 F. to solvent extraction to produce a paraffin-richraffinate and an aromatic rich extract, hydrocracking the raftinateusing a catalyst comprising a hydrogenating component on anoncrystalline amorphous support, recovering ajet fuel from thehydrocracked raffinate, separately hydrocracking the aromatic-richextract using a catalyst comprising a hydrogenating component on asupport comprising a crystalline zeolite and recovering a motor fuelfrom the hydrocracked extract.

The charge stocks used in the process of our invention include anyhydrocarbon oil boiling above about 500 for example atmospheric gasoils, vacuum gas oils, atmospheric residua and the like. The preferredstarting materials are virgin atmospheric gas oils and cycle gas oilsobtained-from the fluid catalytic cracking units.

The charge is subjected to solvent refining using a solvent having anaffinity for aromatics such as S0,, furfural, N- methyl pyrrolidone andthe like. solvent dosages may range from 75-600 percent depending on thesolvent and the charge stock. Temperatures of 50-250 F. may be used alsodepending on the solvent and charge stocks. Preferred solvents arefurfural of N-methyl pyrrolidone used at dosages of 75-300 percent andtemperature of about 75-l 50 F.

The rafiinate after being stripped of residual solvent is hydrocrackedby being brought into contact with a hydrocracking catalyst at atemperature between about 450 and 900 F., a pressure between about 500and 5,000 p.s.i.g., a space velocity between 0.2 and and a hydrogen rateof 2,000-30,000 SCFB. Preferred conditions are temperatures between 550and 850 F., pressure of l,00O-2,500 p.s.i.g., space velocities between0.5 and 3 and hydrogen rates between 4,000 and 20,000 SCFB.

The catalyst used for the hydrocracking of the raffinate comprises ahydrogenating component on an amorphous support. The hydrogenatingcomponent may comprise a Group Vll metal or compound thereof eitheralone or in conjunction with a Group Vl metal or compound thereof. Whenthe hydrogenating component is a noble metal such as platinum,

palladium, sodium and the like, it is used in amounts between 0.1 and 5percent, preferably between 0.2 and l percent based on the weight of thecatalyst composite. When the hydrogenating component comprises an irongroup metal or compound thereof, it may be used alone but preferably itis used in conjunction with a Group Vl metal such as molybdenum ortungsten or compounds thereof. In such event, the iron group metal maybe present in an amount between about 2-20 percent, preferably 5-l0percent by weight based on the catalyst composite and the Group V] metalmay be present in an amount between about 5 and 35 percent, preferablybetween 6 and 25 percent by weight. Examples of combinations of Group V]and Group Vlll metals are cobalt-molybdenum, nickel-molybdenum andnickel-tungsten. Advantageously the catalyst contains a minor amount ofhalogen such as 0.1-5 percent fluorine or chlorine.

The support for the catalyst used in the hydrocracking of the raffinateis composed of one or more amorphous inorganic oxides such as silica,alumina, zirconia, magnesiaandthe like. The preferred support is amixture of silica and alumina containing from about 50-80 percent silicaand 50-20 percent alumina by weight. A preferred catalyst contains 6percent nickel and 19 percent tungsten on a support composed of 73percent silica and 27 percent alumina. Advantageously, the catalyst issulfided prior to use.

After the solvent has been removed from the extract as for example bydistillation and stripping,'the extract is subjected to hydrocracking.The conditions used for the hydrocracking of the extract such astemperature, pressure, space velocity and hydrogen rate aresubstantially the same as those used for the hydrocracking of theraffinate. However, the catalyst which contains a hydrogenatingcomponent such as (and which may be the same as) that of the catalystused for the hydrocracking of the raffmate also contains a support whichincludes about 8-60 percent by weight of the support of a crystallinezeolitic alumino silicate. The crystalline portion of the support hassubstantially uniform pore openings of from 6-l 5 Angstroms and has analkali metal content of less than 5' percent and preferably less than 1percent. Suitably the crystalline portion of the support may be preparedby subjecting zeolite Y to ion exchange treatment with a solution of anammonium salt to reduce the alkali metal content to about 3 percent. Thezeolite is then washed, dried and calcined at a temperature of aboutl,200 F. for several hours the calcined zeolite is then subjected to asecond .ion exchange treatment with a solution of an ammonium salt toreduce the alkali metal content to less than 1.0 percent, washed, driedand again calcined at a temperature of at least about l,000 F. forseveral,

hours. The zeolite is then mixed with an amorphous inorganic oxide toprovide the support for the hydrogenating component. Preferably, thebalance of the support comprises a mixture of silica and aluminacontaining from 50-80 silica and 50-20 percent alumina. A preferredcatalyst contains 6-8 percent nickel and 22 percent tungsten on asupport containing 24 percent decationized zeolite Y, 57 percent silicaand I9 percent alumina.

The effluents from the two hydrocracking units may be combined andfractionated to recover a motor fuel fraction and a jet fuel fraction,that portion of the effluent boiling above the jet fuel range beingrecycled to a fluidized catalytic cracking unit. Alternatively theeffluents may be fractionated separately to recover motor and jet fuelswith recycle of the unconverted material. In a preferred embodiment thehydrocracked product boiling above the jet fuel range, whether obtainedfrom the rafilnate or the extract is recycled to the solvent extractionzone.

When the charge to the system has a relatively high basic nitrogencontent e.g., above about ppm. nitrogen, it may be subjectedto adenitrogenation treatment such as by contacting the charge with acatalyst such as nickel molybdate on alumina, in a manner well known tothe art, to convert the nitrogen therein to ammonia which is removedprior to the solvent extraction step. However when the catalyst used forthe hydrocracking of the extract is composed of nickel and TABLE 111tungsten on a zeolite containing base as described above, then RamnateEmmi; it is not necessary to subject the entire charge to a gdenitrogenation and it is sufficient to subject only the raffinateIsobutene 4. 06 4. 78 2. 36 3. 88 to nitrogen removal prior tohydrocracking. The nickel tung Butane 2 09 L 54 0 60 Q 97 sten sulfidezeolite-based catalyst 18 particularly resistant to Isommanes 4 29 gig3,4 n-Pentane 0.93 0.60 6 nitrogen poisoning and therefore the extractneed not be given H35, F. gasoline 1M5 13. 42 5. 77 9. M thisaddltlonaltreatment- 235-325 F. gasoline 19.42 1.23 16.37 '26. 1a325525" F.1etiuel 44. 55 9 The hydrogen used m our process need not bepure. Total 04+ 9Q 09 76 62 63 44. 62 Hydrogen of 70 percent purity maybe used but a hydrogen purity of at least 85 percent is preferred.2354017 Easmine- The following examples are given for illustrativepurposes For comparative purposes harge stocks A and B are ub. yjectedto hydrocracking using both the amorphous and Charge A i an atmosphericg il in fro South zeolite-based catalysts specified above undercomparable Louisiana Light Regular Crude and Charge 3 cycle gas oiloperating conditions. Yield date are shown in Table IV.

' TABLE IV Zeolite Amorphous Zeollte Amorphous H consumption, s.c.l.b1,500 1,090 1,734 1,015 Isobutane, volume percen 15.88 5.10 6.72 7.57n-Butane, volume percent. 8. 44 2. 68 5. 66 2. 46 Isopetanes, volumepercent 19. 5. 48 8. 62 ti. .14 n-Pentenes, volume percent 2.00 1.10 2.47 1. 43 115-235 F. gasoline, volume percent.. 34. 36 10.32 18. 88 15.82235-325 F. gasoline, volume percent. 26. 54 24. 31. 26 30. 411 Totalgasoline 60. 81 43. 77 50.14 46. 31 325525 F. jet fuel, volumepercent... 16.16 57.07 45. 42 54. 84 Total 115-525 F., volume percent...76.97 100.84 15. 56 101.15 Total 04+, volume percent 122. 115. 38 110.03110.

obtained from a fluid catalytic cracking unit. The characteristics l e res ersseliertli sle leblsl.

TABLE I Gravity, API 30. 6 2s. 3 ASTM distillation, F.: 35 IBP-5 513-539392-466 10-20. 556-580 508-553 30-40. 600-622 578-604 50 640 626 60-70.662-684 646-665 -90. 714-754 686-718 595-111. 760+ 750-760-l- 40 Sulfur,X-ray, wt percen 0. 15 0.18 Basic nitrogen, p.p.m 61 26 Total nitrogen,p.p.m 111 98 Total aromatics, wt. percen 23. 5 38. 1 Polycyclicaromatics, wt. percen 8. 66 29. 3

Charge A is subjected to solvent extraction with furfural 45 (containing5 percent water) at a dosage of 75 volume percent and a temperature ofF. to obtain a yield of 79.5 volume percent of a raffinate containing8.8 volume percent aromatics and 20.5 volume percent of an extractcontaining 80.0 volume percent aromatics. Solvent extraction of Charge B50 with furfural (5 percent water) at a dosage of volume percent and atemperature of 90 F. yields 66.7 volume percent of raffinate containing17.1 percent aromatics and 33.3 volume percent of extract containing80.0 volume percent aromatics.

Hydrocracking conditions for the extracts and raffinates appear below inTable II. In each case for the hydrocracking of the extract the catalystcontains 7.9 weight percent nickel oxide and 24.7 weight percenttungsten oxide on a support containing 24 percent decationized zeoliteY, 57 percent silica and 19 percent alumina whereas the catalyst for thehydrocracking of the raftinate contains 6.5 percent nickel, 21 percenttungsten, 51 percent silica, 18 percent alumina and 1.5 percentfluorine. Also, in each case, the catalyst is sulfided A comparison ofthe gasoline produced by the various 7 30 procedures exemplified aboveappears in Table V. Column 1 represents the process of our invention inwhich the charge is solvent extracted and the raffinate and extracthydrocracked separately using amorphous and zeolite based catalystsrespectively. Column 2 represents the process in which'the total chargeis hydrocracked over the zeolite-based catalyst and Column 3 in whichthe total charge is hydrocracked over t e v eessslely t TABLE V Chargestock 1 2 Z1 -235 F. fraction:

Gravity, API. 70. 6 73. 5 68. 5 Research octane ar.-. 74.0 72.0 70.5Plus 3 c 91. 5 .11. 0 811. 0 235-325 F. fraction:

Gravity, API 56. 5 56. 5 55.11 Research octanes:

Clear 50. 0 (12. 5 50. 0 Plus 3 cc. TEL 70. 0 81. 5 70. 5 235400 F.fraction:

Gravity, API 4855 Research octanes:

Clear 72.0 Plus 3 cc. TEL 88.0 Octane barrels at 3 cc.: TEL basis 100bbls.

charge 5, 765 4, 265 3, 832

Table VI below shows the jet fuel quality comparison between jet fuelsprepared by our process and those prepared by hydrocracking the charge.in Table VI Columns 1 and 3 show the characteristics of the product whenthe total charge is hydrocracked using a sulfided nickel tungsten silicaalumina catalyst and Columns 2 and 4 when the rafflnate is hydrocrackedusing a sulfided nickel tungsten on silica-aluprior to use. minacatalyst (Table 111). WW W 7 TABLE II Rulllne to Extract RuillnuteExtract 'lcmpumturo, l" 075 715 700 725 l'russurv, p.s.i.g 1. 500 1,5001,500 1,500 He luto s.r.l./l1l1l. l'vcCL 0, 000 (l, 000 0, 000 (l, 000IIISV, 'o/llix/Vr U 1.0 l. 1.0 1.0 l'ur puss conversion, volumn pcrccnt30.0 70.0 30. 0 70.0

Yields from the hydrocracking of the raffinates and extracts in terms ofvolume percent based on the total charge appear in Table III.

From the foregoing it can be seen that the process of our inventionproduces motor fuel and jet fuel in greater yields and of better qualitythan conventional processes.

mam vi Charge stock 1 2 3 4 Gravity API...-.- 45.6 48 43.7 47 AS'IMdistillation, a

348 350 347 350 95%- 488 490 498 490 EP 503 510 529 510 Freeze point, F--64 65 52 -65 Flash point, F.- 113 120 120 120 Smoke point, mim 30 4028 38 Lumlnometer number 64 86 61 83 FIA analysis, volume percent:

romatics 5. 4 2. 0 5. 8 2. 6 Olefins 1. 4 Trace 0.8 Trace Dlnucleararomatics, wt. percent 0. 06 Trace 0. 24 Trace It is also possible torecycle unconverted material into the system. For example that portionof the hydrocracked raffinate boiling above the jet fuel range may berecycled to the catalytic cracking zone, to the solvent extraction zoneor to the raffmate hydrocracking zone. Similarly that portion of theextract boiling above the motor fuel range may be recycled to thecatalytic cracking zone, the solvent extraction zone or to the extracthydrocracking zone. Various other modifications of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof and therefore only such limitations should be imposed asare indicated the support in an amount between 8 and 60 percent byweight .of the support.

4. The process of claim 1 in which each hydrogenating componentcomprises a Group VIII metal or compound thereof.

5. The process of claim 4 in which the catalyst used for theihydrocracking of the rafi'mate comprises nickel and tungsten.

6. The process of claim 4 in which the catalyst used for thehydrocracking of the extract comprises nickel and tungsten.

7. The process of claim 1 in which the gas oil is derived from acatalytic cracking reaction and that portion of the ihydrocrackedraffinate boiling above the jet fuel range is retumed to the catalyticcracking zone.

8. The process of claim 1 in which that portion of the hydrocrackedextract boiling above the gasoline range is returned to the solventextraction zone.

9. The process of claim 2 in which the crystalline zeolite has beenprepared by subjecting zeolite Y to a treatment comprising ion exchangewith a solution of an ammonium compound, calcination, a second ionexchange with a solution of an ammonium compound and a secondcalcination.

2. The process of claim 1 in which the crystaline zeolite has an alkalimetal content of less than 1 percent by weight.
 3. The process of claim1 in which the zeolite is present in the support in an amount between 8and 60 percent by weight of the support.
 4. The process of claim 1 inwhich each hydrogenating component comprises a Group VIII metal orcompound thereof.
 5. The process of claim 4 in which the catalyst usedfor the hydrocracking of the raffinate comprises nickel and tungsten. 6.The process of claim 4 in which the catalyst used for the hydrocrackingof the extract comprises nickel and tungsten.
 7. The process of claim 1in which the gas oil is derived from a catalytic cracking reaction andthat portion of the hydrocracked raffInate boiling above the jet fuelrange is returned to the catalytic cracking zone.
 8. The process ofclaim 1 in which that portion of the hydrocracked extract boiling abovethe gasoline range is returned to the solvent extraction zone.
 9. Theprocess of claim 2 in which the crystalline zeolite has been prepared bysubjecting zeolite Y to a treatment comprising ion exchange with asolution of an ammonium compound, calcination, a second ion exchangewith a solution of an ammonium compound and a second calcination.